For nearly 40 years marijuana has remained the most widely used illicit drug in the US, with more than 50% of first-time users < age 18. Marijuana accounts for H 60% of illicit substance use disorders (SUD) in the US, bearing by percent the largest US public health burden among illicit substances. Across preclinical, human laboratory, and clinical interview data, there is compelling evidence that the phenomenon of cue reactivity is related to drug seeking and relapse. Attentional bias is a measurable component of cue reactivity, and can be operationally defined as differential attention (e.g., reaction time difference) towards drug-related stimuli vs. neutral stimuli. This phenomenon has been demonstrated in SUD populations across many classes of abused drugs, including alcohol, nicotine, stimulants, opiates, and - importantly - marijuana. Cue reactivity and attentional bias are exacerbated by acute and chronic stress and anxiety. Notably, stress is a well-documented predictor of marijuana abuse and marijuana relapse. Therapeutic interventions that attenuate attentional bias to marijuana cues are a potentially important component in the treatment of marijuana SUD. Due to the well-documented association with stress, an intervention that simultaneously addresses both stress and attentional bias could be uniquely efficacious. Currently, few pharmacotherapies exist for marijuana SUD, and none are presently known to address attentional bias to marijuana cues. This application will explore the potential of the anxiolytic buspirone to modify attentional bias and stress. Buspirone is a unique compound marked by modulation of both 5-HT1A and D3 receptors. Importantly, the 5-HT1A receptor is known to play a key role in stress- related anxiety, and preclinical work indicates that D3 antagonists significantly decrease cue reactivity to a number of abused drugs. This combination of effects suggests buspirone may be advantageous in targeting both stress and attentional bias as factors that contribute to problem marijuana use. Accordingly, this application seeks to examine the effects of chronic buspirone administration on attentional bias and stress/anxiety in marijuana SUD. Using laboratory-based methodologies sensitive to attentional bias towards marijuana cues and well validated measures of stress and anxiety, we will examine if buspirone' s unique mechanism of action will (a) produce an attenuation of attentional bias to marijuana cues, and (b) be most pronounced under conditions in which attentional bias is related to high levels of stress and anxiety. !